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  #16  
Old 09-02-2009, 09:19 PM
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I've replaced three in the past 2years (different cars), it cured the symptoms each time.

Very common failure, there's even an engineering change to the original relay (different part number).

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  #17  
Old 09-02-2009, 11:34 PM
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My 89 300sel has had the engine light on for awhile. The other day, after reading about code( mine was 4)...I pulled it off its mount, tried to unplug it(did not want to break) moved it around and checked fuse. Replaced it and the engine light went off!!! For 2 days no problem...ran great, but I turned on a/c which does not work just to put a load on and bam the light came back on. Went thru the same exercise and light went off again.

Any ideas, suggestions as to why. I do have issues with a/c...heater is always on it seems......
Thanks and the lil box is important!!!!!!!!!!!!1
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  #18  
Old 09-03-2009, 06:47 AM
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Quote:
Originally Posted by ps2cho View Post
If the ABS light is on and your ABS is functional -- It's the OVP...
Is this so? Since the OVP is the power source for the ABS controller, if the OVP is bad and the ABS light is on, it's because the ABS controller (and, therefore, the ABS system) is inop. Isn't that so?

Quote:
Originally Posted by ps2cho View Post
...I've never heard of the light come on for any other reason...
My ABS light was on because of a bad speed sensor on one of the front wheels. In my case, the OVP was fine.
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1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
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Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

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  #19  
Old 09-04-2009, 09:21 AM
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Quote:
Originally Posted by Rafi View Post
I have never dealt with OVP. What years and Models have OVP?
It would take a bit of research to get a complete and precise answer, but generally speaking, most MB chassis during the 80s and up to about model year 1995 had an OVP, although it seems to have been more common on 6-cylinder motors than on V8s. I don't know its usage on pre-80s cars, but probably not, inasmuch as the electronics on earlier chassis were simpler (no computers), and the OVP is there basically to protect some expensive, sensitive control units. Maybe a professional tech can give a more complete answer.
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1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't
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  #20  
Old 09-05-2009, 10:28 PM
89 Mercedes 300e,190 000k
 
Join Date: Dec 2008
Location: windsor, ontario, canada
Posts: 74
Alright guys i swapped the Ovp from the 91 300e to my 89 300e and still broken. I then took the ovp and started the car and it took longer to start and the ABS light was on and ran even more rougher than right now. So OVP is out of the question whats next?
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  #21  
Old 09-06-2009, 07:03 AM
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Allen, you don't say what maintenance history is or what else has recently been done to the car since your symptoms first appeared. It's time to haul out the multimeter and the CIS fuel pressure tester and start systematic diagnostic testing of the ignition/electrical and fuel systems. The tests themselves are surprisingly easy and quick to perform. That will begin to narrow down the list of possible causes. Then post back any results that are questionable and you'll no doubt get knowledgeable help.
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1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't
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  #22  
Old 09-06-2009, 03:06 PM
whunter's Avatar
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Location: Metro Detroit, Michigan
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OVP data

OVP relay, Over Voltage Protection Links
OVP relay, Over Voltage Protection Links


Code data..

Jim Forgione's DIY articles
http://www.k6jrf.com/MB_S500.html




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  #23  
Old 09-06-2009, 05:30 PM
89 Mercedes 300e,190 000k
 
Join Date: Dec 2008
Location: windsor, ontario, canada
Posts: 74
The car had all the necessary tune ups 1 or 2 years ago, plugs wires distributor cap/rotor, full tune up. Heres the story. The problem where i press the gas and go no where (flat spots) happened awhile back. So i brought my car to my mechanic and we put a gas analyzer in the exhaust. The car was running as rich as possible. So buy turning the screw over the intake manifold we brought down the Ho, Co2, then i drove around for about a week and was noticing that when i stoped at a light the whole car started shaking and rpms droped, vacuum was at the middle/red like it does now but when the car reached optimal temperature it stopped doing it, , . So i brought it back to the mechanics and his solution was to up the richness of the fuel basically to mask the problem. It worked though for about a year all of a sudden it happened again in like June of this year but now it happens all the time even at optimal temperature. So im kind of hoping for something to break or coming up with a real solution. I dont have the necessary tools to diagnose the car..
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  #24  
Old 09-07-2009, 01:17 PM
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Have you checked: Temperature sensor, fuel pressure (filters and pump operation).

The temperature sensor enables cold enrichment and if reading cold, could cause the car to run rich.

The fuel pressure is an important part of the fuel mix also: When fuel pressure is low in a CIS system, the counter-pressure on the metering pin will be low and allow the air-flow sensor plate to rise too far, injecting too much fuel. If the fuel pressure is lower still, the car will not run well due to inadequate fuel flow and pattern. Fuel filters can be a culprit here and are a good place to start if they haven't been serviced.
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  #25  
Old 09-07-2009, 10:31 PM
89 Mercedes 300e,190 000k
 
Join Date: Dec 2008
Location: windsor, ontario, canada
Posts: 74
temperature sensor?

I replaced the fuel filter thinking it was the culprit but no luck, the fuel pressure is fine also. How ever my car has the strangest symptoms from different temperature like it took almost the entire battery to start the car every day in the winter, also in the rain its hard to start. Where and how do i check the temperature sensor because there is a good chance that something is wrong with it. Please help thanks
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  #26  
Old 09-07-2009, 10:45 PM
mak mak is offline
mark
 
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ovp

Quote:
Originally Posted by lorainfurniture View Post
I had the same ABS light and then flashing check engine light... I suspected my ovp for months now. Was never able to catch it in the act.. Finally just changed it, 3 days, and no symptoms..

Plugs and wires may cause some symptoms, but the abs light would lean me towards the ovp or elsewhere.
inside the OVP the solder connections near the large diode open up .resoldering works ,but i belive the best is to replace the OVP and the fuel relay togather at this stage for dependability
mak

300se
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  #27  
Old 09-07-2009, 11:25 PM
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OVP

I am getting the same symptoms with my 1989 300E. Intermittent ABS light with check engine light. Goes on and off! I also suspected the OVP relay so I finally ordered a new one. Hope it solves the problem...............
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  #28  
Old 09-08-2009, 07:13 AM
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Quote:
Originally Posted by allenbistany View Post
Where and how do i check the temperature sensor because there is a good chance that something is wrong with it. Please help thanks
The temp sensor is located on the top of the engine block on the left side of the valve cover, all the way at the back of the engine. There's a large black electrical connector plugged onto it, and its wire runs over to the left inner fender and ends in a 4-pin connector plugged into the ignition control unit there. The sensor is tested with an ohmmeter at various engine temperatures, and the results compared against a resistance-to-temperature chart printed in any good service manual. To perform these tests, you need a multimeter, available for about $25 at Sears, and a good service manual to walk you through the test procedures and give you the resistance specs for the relevant electrical component you intend to test. As already mentioned, the tests themselves are quite easy and quick to perform, anybody can do them. Of course, the alternative is to simply replace the sensor and see if that corrects the symptoms.
__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't
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  #29  
Old 09-08-2009, 04:27 PM
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Correct me if I'm wrong, it's been about 13years since I last had a 103-powered Mercedes, but from memory it seems that you can see the airflow-meter plate with the air-filter assembly removed.

Anyway, gain access to the airflow-meter, take a magnet (one of those magnet-on-a-pen things usually works well if it's strong enough) and touch it to the bolt in the center of the airflow meter plate, see if you can lift it. It should lift smoothly, without scraping the sides of the bore. Also, it should rest with the top surface just about the same level as the bottom of the tapered part of the bore. If either of these things are not true, it needs a simple adjustment to correct it.

I have had several cars (mine and friends') which for no reason I know, have gotten to a point where the metering plate will touch the sides and drag a bit. When this happens, the cranking vacuum will not lift the plate enough to provide adequate fuel, even with a wide-open throttle. VERY easy adjustment but be careful and ask questions first.

If it got that way after needing some throttle to start, sounds like a possibility. This also affects mixture at idle some times.

The other common problem in that system for hard-starts is the cold-start injector or the temp sensor, not providing the extra fuel shot to start the cold engine.
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  #30  
Old 09-08-2009, 10:43 PM
89 Mercedes 300e,190 000k
 
Join Date: Dec 2008
Location: windsor, ontario, canada
Posts: 74
Alright you guys are awesome thanks for your help. I do have a voltmeter and I know a bit about about electricity but i will ask if i get into a problem. Today it was pouring rain and the car took 3 long cranks to start, now some people were skeptical about me saying that it is moisture/temperature related but i honestly am 100% sure it is. I have another tread about hard starting but it was never resolved because summer came and i never had a problem since, but I am thinking that the rough idle is some how inter related and winter is around the corner so I need to get this fixed. Could someone get me a link or a page of the multimeter testing for the temp sensor and hopefully a walk through. Also the magnet check seems simple enough so I will give that a try as well. Thanks ill keep you guys posted.....

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